What is "O KY"? Are you talking about federal tax or state tax that was withheld from your 401(k) withdrawal? If it's state tax, what state is it? Kentucky? Is that what "KY" is? Kentucky income tax is only 5%. The 20% withholding sounds like federal tax, not state.
Income tax is not calculated separately for the 401(k) withdrawal. Your income tax is calculated on your total income for the year. The tax withheld from the 401(k) withdrawal is combined with any tax that is withheld from other income, and the total amount of tax withheld from all sources is applied to your total tax. That includes tax withheld from your pay or any other income. To estimate how much tax you will owe, you have to estimate your total tax for the year and the total amount you will have withheld for the year. You might not need to make any additional payment.
Was this an early withdrawal? If so, you will have to pay a 10% penalty in addition to the regular federal income tax. You have not indicated that you have done anything that would avoid the tax or the penalty. What did you do with the money?
